1. Field of the Invention
The present invention relates to a perceived passive reuse prevention syringe that uses a retaining ring lock. More specifically, the present invention relates to a syringe that includes a retaining ring on the inside surface of a syringe barrel for engaging a plunger head, which includes the sealing surface of a plunger assembly. After the plunger head has entered the locked position, attempting to withdraw the plunger assembly from the syringe barrel will result in the plunger assembly breaking into two pieces with the plunger head remaining in the syringe barrel.
2. Description of Related Art
In the United States and throughout the world, the multiple use of hypodermic syringe products that are intended for single use only is instrumental in drug abuse and more particularly, in the transfer of diseases. Intravenous drug users who routinely share and reuse syringes are a high risk group with respect to the AIDS virus. Also, the effects of multiple use are a major concern in under-developed countries where repeated use of syringe products may be responsible for the spread of many diseases. Reuse of the single use hypodermic syringe assemblies is also instrumental in the spread of drug abuse even in the absence of infection or disease.
Many attempts have been made to remedy this problem. Some of these attempts have required a specific act to destroy the syringe after use either by using a destructive device or providing a syringe assembly with frangible zones so that the syringe could be rendered inoperable by the application of force. Other attempts involve the inclusion of structure which would allow the destruction or defeating of the syringe function to a conscious act by the syringe user. Although many of these devices work quite well, they do require the specific intent of the user followed by the actual act to destroy or render the syringe inoperable. These devices are not effective with a user having the specific intent to reuse the hypodermic syringe.
Attempts have also been made to provide an automatic function to disable or render a syringe assembly inoperable after a single or select number of uses. However, such an automatic function is harder to provide because the means for rendering the syringe inoperable must not prevent its filling or use under normal conditions. Moreover, typical automatic locking and disabling devices only allow for a fixed dosage amount to be supplied by the syringe before the syringe is disabled.